feat(getStringByteLength): 新增 getStringByteLength 方法，获取字符串的字节长度

src/getStringByteLength.ts

@@ -0,0 +1,17 @@
+/**
+ * 获取字符串的 UTF-8 子节长度
+ *
+ * @param str - 字符串
+ * @param index - unicode 的下标
+ * @returns 字节长度
+ *
+ * @example
+ * ```ts
+ * getStringByteLength(‘ABC’) // 3
+ * getStringByteLength(‘哈喽’) // 6
+ * ```
+ * @see [Stack Overflow: String length in bytes in JavaScript](https://stackoverflow.com/questions/5515869/string-length-in-bytes-in-javascript)
+ * @beta
+ */
+export const getStringByteLength = (str: string) =>
+  new TextEncoder().encode(str).length

test/getStringByteLength.test.ts

@@ -0,0 +1,45 @@
+import assert from 'assert'
+import { TextEncoder } from 'util'
+import { getStringByteLength } from '../src/getStringByteLength'
+
+global.TextEncoder = TextEncoder
+
+describe('getStringByteLength:', () => {
+  /**
+   * number and letter
+   */
+  describe('number and letter', () => {
+    test(' "123" => 3 ', () => {
+      assert.strictEqual(getStringByteLength('123'), 3)
+    })
+    test(' "ABC" => 3 ', () => {
+      assert.strictEqual(getStringByteLength('ABC'), 3)
+    })
+  })
+
+  /**
+   * Chinese
+   */
+  describe('Chinese', () => {
+    test(' "哈" => 3 ', () => {
+      assert.strictEqual(getStringByteLength('哈'), 3)
+    })
+
+    test(' "阿斯顿" => 9 ', () => {
+      assert.strictEqual(getStringByteLength('阿斯顿'), 9)
+    })
+  })
+
+  /**
+   * Emoji
+   */
+  describe('Emoji', () => {
+    test(' "😂" => 4 ', () => {
+      assert.strictEqual(getStringByteLength('😂'), 4)
+    })
+
+    test(' "👨‍👩‍👦" => 18 ', () => {
+      assert.strictEqual(getStringByteLength('👨‍👩‍👦'), 18)
+    })
+  })
+})